Wedge clutch for a camshaft phaser

ABSTRACT

A wedge clutch for a camshaft phaser is disclosed. The wedge clutch includes a stator including a pressure plate. The wedge clutch further includes a wedge plate including a notch. The notch includes a pulling surface. The wedge clutch further includes a rotor including a pin inside of a chamber. The pin is configured to rotate the wedge plate in a first circumferential direction relative to the rotor by sliding along the pulling surface as the pin extends out of the chamber to disengage the wedge clutch from the pressure plate.

FIELD OF INVENTION

The present invention relates to a camshaft phaser, and, moreparticularly, to a wedge clutch for a camshaft phaser.

BACKGROUND

A clutch is a mechanism that controls rotational motion. Clutches areoften found in engines and transmissions as a means to control relativerotation of a rotor and a stator. For example, U.S. Patent ApplicationPublication No. 2009/0159390 to Davis discloses a friction one-wayclutch for a transmission. The clutch includes a wedge ring thatselectively engages a stator to prevent the stator from rotating in onedirection.

Wedge clutches are also used in conjunction with cam phasers forengines. For example, a cam phaser may advance or retard the position ofa camshaft relative to the crankshaft of the engine based on thepositioning of one or more wedge clutches in order to improveefficiency.

However, it is difficult to control the positioning of a wedge clutch.Hydraulic pressure is often used for this purpose, but is notefficiently utilized in current designs. The present disclosure isdirected to overcoming this and other problems of the prior art.

SUMMARY

In one aspect, a wedge clutch is provided. The wedge clutch includes astator including a pressure plate. The wedge clutch further includes awedge plate including a notch. The notch includes a pulling surface. Thewedge clutch further includes a rotor positioned radially between thepressure plate and the rotor and including a pin inside of a chamber.The pin is configured to rotate the wedge plate in a firstcircumferential direction relative to the rotor by sliding along thepulling surface as the pin extends out of the chamber to disengage thewedge plate from the pressure plate.

In another aspect, a camshaft phaser is provided. The camshaft phaserincludes a stator configured to receive torque from a crankshaft and arotor configured to be non-rotatably connected to a camshaft. The rotorincludes a plurality of first ramps and a pin inside of a chamber. Thecamshaft phaser further includes a first wedge plate. The first wedgeplate includes a plurality of second ramps engaging the plurality offirst ramps, and a notch including a pulling surface. The camshaftphaser further includes a pressure plate configured to engage the firstwedge plate. The pin is configured to disengage the first wedge platefrom the pressure plate by sliding along the pulling surface as the pinextends out of the chamber.

BRIEF DESCRIPTION OF THE DRAWING(S)

The foregoing Summary and the following detailed description will bebetter understood when read in conjunction with the appended drawings,which illustrate a preferred embodiment of the invention. In thedrawings:

FIG. 1 shows a perspective exploded view of a camshaft phaser.

FIG. 2 shows a front view of the camshaft phaser of FIG. 1.

FIG. 3 shows the camshaft phaser of FIG. 1 in a locked position.

FIG. 4 shows the camshaft phaser of FIG. 1 in an unlocked position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

FIG. 1 shows an exemplary camshaft phaser 10. The camshaft phaser 10includes an axis of rotation AR, and a wedge clutch 11. The wedge clutch11 includes a rotatable stator 12 configured with teeth on acircumferential surface to receive torque from the crankshaft of aninternal combustion engine (e.g., via a timing belt, chain, or gear), arotatable rotor 14 configured to be non-rotatably connected to acamshaft, a first wedge plate 16A and a second wedge plate 16B radiallydisposed between the rotor 14 and the stator 12, and a displacementassembly 18. The first and second wedge plates 16A, 16B have ramps 24,44, respectively, that are oriented in opposite circumferentialdirections. While the camshaft phaser 10 is depicted and described asincluding two one-way wedge clutches, it should be understood that thepresent disclosure encompasses embodiments that include one or morewedge clutches (e.g., one or more wedge plates).

The stator 12 includes a pair of pressure plates 20 configured toreceive a pressure force from the wedge plates 16A, 16B to preventrotation of the rotor 14 relative to the stator 12. In some embodiments,the pressure plates 20 may be integrally formed with the stator 12. Therotor 14 is positioned in the stator 12. The rotor 14 is configured torotate relative to the stator 12 in both directions when the first wedgeplate 16A and/or the second wedge plate 16B is disengaged from thecorresponding pressure plate 20.

The relative positioning of the rotor 14 and the stator 12 determines aphase between the rotational input at the stator 12 and the rotationaloutput at the rotor 14 (e.g., between a timing belt, chain, or gear anda camshaft). The rotor 14 may be “advanced” through rotation in a firstcircumferential direction CD1 relative to the stator 12. The rotor 14may be “retarded” through rotation in a second circumferential directionCD2, opposite from the first circumferential direction, relative to thestator 12. The displacement assembly 18 is configured to control theposition of the rotor 14 relative to the stator 12 via the wedge plates16A and 16B.

FIG. 2 shows one side of the assembled camshaft phaser 10. Inparticular, the side of the camshaft phaser 10 that includes the firstwedge plate 16A is shown. The first wedge plate 16A is configured toadvance the rotor 14. For example, displacement assembly 18 isconfigured to displace the first wedge plate 16A in the firstcircumferential direction CD1 to enable rotation of the rotor 14, withrespect to the stator 12, in the first circumferential direction CD1.

The opposite side of the camshaft phaser 10 includes the second wedgeplate 16B and functions in substantially the same manner as the firstwedge plate 16A to selectively retard the rotor 14. For example, thedisplacement assembly 18 is configured to displace the second wedgeplate 16B in the second circumferential direction CD2, to enablerotation of the rotor 14, with respect to the stator 12, in the secondcircumferential direction CD2.

The rotor 14 includes, on the side shown in FIG. 2, a first plurality oframps 22 that define an engagement surface for the ramps 24 of the firstwedge plate 16A. A radial location of the engagement surface of theramps 22 decreases in the first circumferential direction CD1 andincreases in the second circumferential direction CD2. That is, thefirst plurality of ramps 22 slope radially inward in the firstcircumferential direction CD1 and radially outward in the secondcircumferential direction CD2. The rotor 14 further includes, on theopposite side not shown in FIG. 2, a second plurality of ramps 28 thatslope in an opposite direction (e.g., radially outward in the firstcircumferential direction CD1).

The ramps 24 on the first wedge plate 16A define a correspondingengagement surface for contacting the engagement surface of the firstplurality of ramps 22. A radial distance of the ramps 24 decreases inthe first circumferential direction CD1 and increases in the secondcircumferential direction CD2. That is, the ramps 24 slope radiallyinward in the first circumferential direction CD1 and radially outwardin the second circumferential direction CD2. The ramps 44 on the secondwedge plate 16B slope in an opposite direction of the ramps 24 (e.g.,radially outward in the first circumferential direction CD1).

In an exemplary embodiment, the displacement assembly 18 includes aresilient element 26, such as a spring, on each side of the rotor 14.The first resilient element 26 is circumferentially disposed between therotor 14 and the wedge plate 16A and is arranged to displace the firstwedge plate 16A in the second circumferential direction CD2 with respectto the rotor 14 to lock the first wedge plate 16A through engagementwith the corresponding pressure plate 20. The force of the resilientelement 26 causes the ramps 24 to slide along the first plurality oframps 22 on the rotor 14 to cause the first wedge plate 16A to lockagainst the pressure plate 20, and also eliminates back lash. In thisway, the resilient element 26 forces the wedge plate 16A to maintain anon-rotatable position with respect to the corresponding pressure plate20. The second resilient element 26 similarly forces the wedge plate 16Bto maintain a non-rotatable position with respect to the othercorresponding pressure plate 20.

In order to control a position of the rotor 14 with respect to thestator 12, the first wedge plate 16A and/or the second wedge plate 16Bmay be displaced relative to the rotor 14. For example, the first wedgeplate 16A may be rotated in the first circumferential direction CD1 toslide the ramps 24 of the first wedge plate 16A down the first pluralityof ramps 22 of the rotor 14, thereby moving the first wedge plate 16Ainward toward the center of the rotor 14. This movement causes the firstwedge plate 16A to disengage from the corresponding pressure plate 20,thereby allowing the rotor 14 to rotate relative to the stator 12 in thefirst circumferential direction CD1. Displacement of the second wedgeplate 16B in the second circumferential direction CD2 may similarlydisengage the second wedge plate 16B from the other correspondingpressure plate 20, thereby allowing the rotor 14 to rotate relative tothe stator 12 in the second circumferential direction CD2.

The first and second wedge plates 16A and 16B are therefore configuredto selectively allow the rotor 14 to rotate relative to the stator 12 ineither the first circumferential direction CD1 or the secondcircumferential direction CD2, depending on which of the first andsecond wedge plates 16A and 16B are engaged with the correspondingpressure plates 20. The rotor 14, the first and second wedge plates 16Aand 16B, and the displacement assembly 18 are configured to control thelocking and unlocking of the wedge plates 16A and 16B.

The displacement assembly 18 includes a pin 30. The pin 30 is positionedin a chamber 34 in the rotor 14. In one embodiment, the pin 30 is biasedinto the chamber 34 by a spring 36, although other configurations arepossible.

A notch 32 is formed in the first wedge plate 16A. In an exemplaryembodiment, the notch 32 is positioned adjacent to a free end of thefirst wedge plate 16A. The notch 32 includes a pulling surface 38. Thepulling surface 38 is angled or curved toward an inside of the notch 32as the pulling surface 38 extends radially outward. The wedge plate 16Ais positioned relative to the rotor 14 such that the pulling surface 38is positioned at a top portion of a first ramp 22A of the firstplurality of ramps 22 of the rotor 14.

The notch 32 is further formed by an engagement surface 40 positionedopposite from the pulling surface 38. The engagement surface 40 islonger than the pulling surface 38 such that the engagement surface 40is configured to extend to a position near the bottom of a second ramp22B of the first plurality of ramps 22 of the rotor 14. The first ramp22A may be directly adjacent to the ramp 22B and the resilient element26 may be positioned in a wall 42 between the adjacent ramps 22A and 22Bsuch that the resilient element 26 contacts the engagement surface 40.It should be understood, however, that other arrangements are possible.

FIG. 3 shows the first wedge plate 16A in a locked position. As shown,the pin 30 extends only slightly out of the chamber 34. In thisposition, a top of the pin 30 is positioned near a bottom of the pullingsurface 38. In order to displace the first wedge plate 16A in the firstcircumferential direction CD1 and unlock the first wedge plate 16A, thepin 30 is forced out of the chamber 32, such as to the position of FIG.4.

The pin 30 may be preferably configured to extend out of the chamber 32via hydraulic pressure. For example, a control valve may selectivelydirect hydraulic fluid into the chamber 32, to a base of the pin 30. Thehydraulic fluid acts against the force of the spring 36 to push the pin30 out of the chamber 32. The control valve may also selectively directthe hydraulic fluid away from the pin 30 to remove the pressure andallow the force of the spring 36 to pull the pin 30 back into thechamber 32.

As the pin 30 extends out of the chamber 32, the top of the pin 30slides along the pulling surface 28, thereby forcing the first wedgeplate 16A to rotate in the first circumferential direction CD1, againstthe force of the resilient element 26. Therefore, the pin 30 isconfigured to disengage the wedge plate 16A from the pressure plate 20by sliding along the pulling surface 38 as the pin 30 extends out of thechamber 32. In this way, the pin 30 may be selectively controlled tounlock the first wedge plate 16A from the corresponding pressure plate20, thereby allowing the rotor 14 to rotate in the first circumferentialdirection CD1 relative to the stator 12. The pin 30 may be controlled inany manner known in the art, such as via a hydraulic pressure controlvalve, as described above.

It should be understood that a similar mechanism for locking andunlocking the second wedge plate 16B is provided on the other side ofthe rotor 14. For example, a similar arrangement of a resilient element26, pin 30, and notch 32 may be included and function in substantiallythe same manner in order to selectively disengage the wedge plate 16B toallow the rotor 14 to rotate in the second circumferential direction CD2with respect to the stator 12.

The disclosed wedge clutch 11 provides a mechanism for efficientlycontrolling the positioning of the wedge plates 16A and 16B. Theconfiguration of the notch 32 allows the wedge plates 16A, 16B to bepulled from near a free end of the wedge plates 16A, 16B around therotor 14, which allows for a consistent application of force. Further,the positioning of the notch 32 on each of the respective first andsecond wedge plates 16A, 16B allows the pulling force to be applied nearthe force applied by resilient element 26. This allows the pulling forceto overcome the force of the resilient element 26 more easily. Theseadvantages help to produce a reliable camshaft phaser.

Having thus described the presently preferred embodiments in detail, itis to be appreciated and will be apparent to those skilled in the artthat many physical changes, only a few of which are exemplified in thedetailed description of the invention, could be made without alteringthe inventive concepts and principles embodied therein. It is also to beappreciated that numerous embodiments incorporating only part of thepreferred embodiment are possible which do not alter, with respect tothose parts, the inventive concepts and principles embodied therein. Thepresent embodiments and optional configurations are therefore to beconsidered in all respects as exemplary and/or illustrative and notrestrictive, the scope of the invention being indicated by the appendedclaims rather than by the foregoing description, and all alternateembodiments and changes to this embodiment which come within the meaningand range of equivalency of said claims are therefore to be embracedtherein.

What is claimed is:
 1. A wedge clutch, comprising: a stator including apressure plate; a wedge plate including a notch, the notch comprising apulling surface; and a rotor including a pin inside of a chamber,wherein the wedge plate is located radially between the stator and therotor, and wherein the pin is configured to rotate the wedge plate in afirst circumferential direction relative to the rotor by sliding alongthe pulling surface as the pin extends out of the chamber to disengagethe wedge plate from the pressure plate.
 2. The wedge clutch of claim 1,wherein the pulling surface is angled or curved toward an inside of thenotch as the pulling surface extends radially outward.
 3. The wedgeclutch of claim 1, wherein the notch is positioned adjacent to a freeend of the wedge plate.
 4. The wedge clutch of claim 1, wherein thenotch further includes an engagement surface positioned opposite fromthe pulling surface.
 5. The wedge clutch of claim 4, wherein theengagement surface is longer than the pulling surface.
 6. The wedgeclutch of claim 4, wherein the rotor includes a resilient elementconfigured to apply a force on the engagement surface to bias the wedgeplate in a second circumferential direction, opposite from the firstcircumferential direction to engage the wedge plate with the pressureplate.
 7. The wedge clutch of claim 1, wherein the pin is configured toextend out of the chamber via hydraulic pressure.
 8. A camshaft phaser,comprising: a stator configured to receive torque from a crankshaft andincluding a pressure plate; a rotor configured to be non-rotatablyconnected to a camshaft and including a plurality of first ramps and apin inside of a chamber; and a first wedge plate including a pluralityof second ramps engaging the plurality of first ramps and a notchincluding a pulling surface, wherein the pressure plate is configured toengage the wedge plate, wherein the pin is configured to disengage thewedge plate from the pressure plate by sliding along the pulling surfaceas the pin extends out of the chamber.
 9. The camshaft phaser of claim8, wherein the second plurality of ramps are configured to slide downthe first plurality of ramps to move the first wedge plate inward towardthe center of the rotor, the inward movement disengaging the first wedgeplate from the pressure plate.
 10. The camshaft phaser of claim 8,wherein the rotor further includes a resilient element configured tobias the first wedge plate toward a position in which the wedge plateengages the pressure plate.
 11. The camshaft phaser of claim 10, whereinthe notch further includes an engagement surface positioned oppositefrom the pulling surface, the resilient element configured to apply aforce on the engagement surface to bias the first wedge plate to engagethe pressure plate.
 12. The camshaft phaser of claim 11, wherein theengagement surface is longer than the pulling surface.
 13. The camshaftphaser of claim 11, wherein the pin is positioned near a top portion ofa first ramp of the plurality of first ramps and the resilient elementis positioned near a bottom portion of a second ramp of the plurality ofsecond ramps.
 14. The camshaft phaser of claim 13, wherein the firstramp is directly adjacent to the second ramp.
 15. The camshaft phaser ofclaim 8, wherein the first wedge plate is positioned on a first side ofthe rotor and the camshaft phaser further includes a second wedge platepositioned on a second side of the rotor.